BAW resonators, filters and other components are widely used in high frequency applications such as 4G or long term evolution (LTE) communications to remove unwanted frequencies and improve signal quality. With an effective operating frequency range of 2 gigahertz (GHz) to 16 GHz, BAW components also feature the design advantage of requiring decreased size to accommodate higher bandwidths. This limits their circuitry footprint while making them practical for use in demanding 3 G, 4G and future broadband applications. However, BAW filters are susceptible to unwanted lateral wave propagation that impacts the quality (Q) factor—a measure of the quality of a filter to selectively filter signals at certain frequencies. Lateral waves also cause BAW filters to exhibit spurious resonance mode behavior that superposes the target (expected) BAW resonance mode. Resultantly, the range of frequencies or wavelengths that pass through the BAW filter are unreliable.
A need therefore exists for methodology enabling formation of a BAW resonator and filter that exhibits a high Q factor and improved lateral wave response and the resulting device.